It is commonplace in some regions and in some instances to provide concrete slabs used as floors with a depressed integral lip at the side of surface that co-operates at a later time with an overhead door. The depressed lip prevents surface water from flowing through the door opening onto the more elevated concrete slab finished surface floor.
In finishing concrete slabs of this type, it has been the common practice to screed (i.e. scraping by lateral side movement with a blade) concrete mix from the depressed lip of the slab and afterwards finish the lip surface area by successively troweling the elevated floor with an edging tool and then troweling the edge of the depressed lip with an edging tool, in separate operations using the screed tool as an edging base. Afterwards, it is necessary in a separate step to finish the surface of the depressed lip area.
Each of these three operations is done by hand and the final product is subject to the degree of skill of the operator of the edging tool. The skills are complicated since judgment is required to determine the degree of "set" in the concrete for the proper time to do a good edging and lip surface finishing job. Even with the most skilled, uniformity is not perfect when the separate operations are conducted sequentially.
I have discovered that the operation of providing an integral lip area in a concrete slab door opening may be simplified and several steps eliminated by using a novel hand tool in accordance with the present invention.
Others have sought to simplify concrete finishing edging operations by providing special tools for special shapes, as shown by prior art inventions.
U.S. Pat. No. 1,564,172, Busch, shows a cement finishing trowel which is capable of adjustment by elastic deformation of the finishing surface through adjustment of the handle bolts which determine the length of the finishing surface and therefore the curvature that may be achieved. The purpose of the deformation in this patent is to provide a single variable curb or contoured elevation change. There is no recognition of the multiple levels of mating surfaces that must be maintained. The handle is supported at the ends and perpendicular to the plane of travel and on a line perpendicular to the plane of travel of the tool, making orientation difficult in the line of travel of the tool.
U.S. Pat. No. 1,744,097, Baker et al, shows a mason's molding trowel wherein a relatively complicated molded edge may be provided on the conventional edging tool that is used in concrete finishing. The handle is located in an offset position from the edging operation as is commonly found in a concrete edging tool.
These prior art tools do not meet the needs of the practitioner that are required in situations such as providing the lip on a garage floor surface to receive the garage door and provide a sill. Although there has been a long felt need for a single tool combining all of the features necessary to provide a finished and uniform sill and edge surfaces, the common practice remains to do it in three separate steps with one single edging tool.